\[ -f(x) g\left (x^a y(x)\right )+a y(x)+x y'(x)=0 \] ✓ Mathematica : cpu = 4.2919 (sec), leaf count = 39
\[\text {Solve}\left [\int _1^{x^a y(x)} \frac {1}{g(K[1])} \, dK[1]=\int _1^x K[2]^{a-1} f(K[2]) \, dK[2]+c_1,y(x)\right ]\]
✓ Maple : cpu = 0.273 (sec), leaf count = 33
\[ \left \{ y \left ( x \right ) ={\frac {{\it RootOf} \left ( -\int \!f \left ( x \right ) {x}^{a-1}\,{\rm d}x+\int ^{{\it \_Z}}\! \left ( g \left ( {\it \_a} \right ) \right ) ^{-1}{d{\it \_a}}+{\it \_C1} \right ) }{{x}^{a}}} \right \} \]